Stereoscopic range finder with vertical base



sept. 19, 1944;

w. B. KLEMPERER I 2,358,646

sTnREo'scoPrc RANGE FINDER WITH VERTICAL BASE Filed April 7, 1942 3 Sheets-Shet 1 Septv 1944- I w. B. KLE-MPERER 2,358,646

STEREOSCOPIC RANGEFINDER WITH VERTICAL BASE Filed April 7, 1942 3 Sheet-Sheet 2 3nve'ntor,

Sept. 19, 1944. w K 2,358,646

' STEREOSCOPIC RANGE FINDER WITH vERTIcAy BASE FiId April 7,1943 Sheets-Sheet 5 v j Zmnentor,

h OLFGA/YG 5 AQEM ception in binocular Patented Sept. 19, 1944 orrlca STEREOSCOPIC RANGE FINDER WITH VERTICAL BASE Wolfgang B. Klemperer, Los Angeles, Calif assignor to Douglas Aircraft-Company, Inc, Santa Monica, Calif., a corporation of Delaware Application April 7, 1942, Serial No. 438,050 16 Claims. (ill. 88-2.7)

This invention relates to range finder devices whereby an observer may determine the distance or range of a certain object or target'from the position of the range finder, and the invention comprises improvements important to the art relating to stereoscopic range finders which accompllsh determination of the distance of the target object by the stereoscopic efiect of binoc ular vision enhanced by an exaggerated base or pupillary distance.

An object of the invention is to provide a range finder especially suited for determining the distance of aircraft from the-location of the range finder. Conventional range finders, as used in connection with naval, coast, and field ordnance, have a serious deficiency when attempt is made to apply the mto modern aerial combat, because of the nature of the target. Modern airplanes are highly streamlined, mostly comprising cantilever monoplanes which in the aspect of pursuit or approach appear like not much more than a horizontal blade, the tapered tips of which do not stand out well enough defined to serve as points of rest or determination for the two eyes of the observer when they fuse the two images in binocular vision. Stereoscopic range finders depend for their successful performance on the phenomenon of depth per vision. In the normal position of the human body, with the head erect, the eyes are spaced apart in a horizontal plane, and the optical axes established by the lenses of the eyes lie on opposite sides of median plane intercepting the object being viewed and the midpoint between the eyes. Owing to the above, depth perception in human visionis the result of horizontal perspective, wherein there is a fusing of a, pair of stereoscopic images obtained by eyes spaced on opposite sides of the aforesaid median plane. As the result of this placement'of the eyes, depth .perception-ispbtained from those elements of a field of view which have vertical extension and horizontal spacing, such, for example, as trees, poles, walls, people standing erect, etc., and is not obtained from those elements in the field of view which are horizontally, extended and vertically spaced, such as telegraph wires, roof tops, bodies of water, the horizon, etc.

The conventional.stereoscopic range finder accentuates these depth perceiving characteristics of binocular vision by spreading apart the near ends of the external parts of the two optical axes, this being accomplished by .use of two optical systems, one for each-eye of the observer,

a vertically disposed disposed with their field lenses spaced apart in the horizontalplane of the eyes a distance considerably greater than, and generally a multiple of, the spacing of the eyes. They foregoing observations bring out the fact that in conventional range finders of stereoscopic type the entrance pupils of the objective lenses of the two optical systems are spaced parallel to the spacing of the exit pupils. In ordinary use of conventional range finders, the eye pieces and the objective lenses are spaced apart in a horizontal plane, but it is possible to rotate'the range finder into some other. plane, such, for example, as a vertical plane. However, it is necessary to preserve the relation of the eye pieces and objective lenses, or, in other words, if the range finder is rotated so that its base lies in a vertical plane, the eye pieces and the objective lenses will be spaced in or along a vertical plane, and to use the range finder when vertically, disposed would require rotation of the head of the observer to bring his eyes into vertical'spaced relation in keeping-with the position of the eye pieces of the range finder.

An object of the invention is to provide a range finder of the character described having its base extended along a line disposed at an angle to horizontal, but with the eye pieces thereof spaced apart in a horizontal plane. In disposing the base of the range finder in vertical, position, the invention remedies the difllculties .found in the use of conventional stereoscopic range finders with modern aircraft as the target or object,

and thus makes the stereoscopic range finder aircraft in spite of the physical limitations of.

principle practically applicable to modern aerial combat. Further objects of the invention are to provide a range finder for combat air-planes afiording long'range depth perception of a field of target airplanes in pursuit or defense, to increase the accuracy and speed with which an observer may determine the range of a target space available for accommodation of a range finder in his 'own aircraft.

A further object of the invention is to provide a range finder having a vertical base and horizontally disposed eye pieces wherein the binocular arrangement of the cooperating elementsis preserved so that the,stereoscopic function of depth perception is fully utilized. This valuable result is achieved by the provision of 'means for rotating both of the images obtained through the separate optical systems through an angle of substantially The result 01 this is that the horizontal target aircraft appears in the vision of the observer to be standing on one wing, but this is not detrimental to the achievement of the purpose of the range finder, which is by use of the stereoscopic phenomenon to determine the distance of the object or target from the observer. It has the advantage of presenting the target airplane wing in fore or aft aspect in such a position that its major extension (namely, its span) appears at right angle to the base and offers a distinct mark for judging the stereoscopic parallax in the conjugated optical systems.

Further objects and advantages of the invention will be brought out in the following part of the specification.

Referring to the drawings, which are for'illustrative purposes only,

Fig. .1 is a perspective schematic view showing a preferred embodiment, referred toas type I,

of my range finder and illustrating characteristics of it.

Fig. 2 is a perspective diagram showing the optical elements of which the range finder III of Fig. 1 is composed.

Fig. 3 is a perspective view of a simple form of my invention wherein the upper and lower legs of the range finger are bodily movable in the direction of the eye distance for the purpose of adjusting the spacing of the eye pieces. This. arrangement will be referred to as type Z.

- Fig. 4 is a diagrammatic view showing the op-' tical system of the range flnder shown in Fig. 3. Fig. 5 is a diagrammatic view showing the form of my range finder referred to as type D.

Fig. 6 is a ditic view showing the form of my range finder referred to as type T. Fig. '7 is a ditic view showing the form of my range finder referred to as type Y.

Fig. 8 is a diagrammatic view showing the form of my range finder referred to as type N.

Fig. 9 is a face view of a reticule pattern used in my invention.

In the schematic view, Fig; l, I have shown a range finder "I having a tubular housing ll coinciding with avertical base 3-3. At an intermediate point there is an eye piece housing l2 having a right eye piece RE and a left eye piece LE-lying in an ocular plane p-p which is horizontal and therefore at an angle of substantially 90 from the optical plane of the objectives R0 and 10, secured respectively at the upper and lower ends of the tubular housing II. This objective plane is the one in which the objectives R0 and LO are spaced and therefore includes the base 3-3 and any vertical line extending through the center of the field F, such as the line and since the image ll of the aircraft is derived stereoscopically, it will appear in perspective and to be in apparent depth with reference to markers which will indicate the distance of the plane I I from the range finder Ill.

In Fig. 2 I show a cube 20 to indicate the character of perspective employed, and in this figure and in the following diagrams the elements of the opticalsystem are diagrammatically shown and are not drawn or positioned to scale. In the perspective employed in Fig. 2, lines which extend laterally are shown horizontally as illustrated by the line 2|. Vertical lines are extended vertically as indicated at 22 and lines which extend from front to rear and perpendicular to vertical and horizontal lines are shown diagonally as indicated at 23. Thestereoscopic image received by the right eye of the observer through the eye piece RE passes from the aircraft I3 along a line -24 to a prism 25 forming a part of the upper objective R0. Below the prism 25 there is an objective lens is. followed by a reticule 21 having thereon markers 21'. The reticule 21 may be positioned in either the first or the second focal plane, but it is preferably positioned in the focal plane of the objective lens 26, as shown, so as to avoid to the greatest extent any errors resulting from distortion of the housing supporting the other optical members. Below the reticule 21 there is a refiectotr shown as a mirror 28, diagonally placed so as to receive the image along the line 38 and to transmit the same along the line 34 to a prism 29 arranged to reflect the image rightward along theline 35 through a complement of erecting lenses III to a prism 3| which reflects the image downward as indicated by the line 36 and then leftward as indicated by the line ll. A diagonal reflector 32 is placed so as to reflect the image toward the observer along the horizontal line 38 which passes through the eye piece RE. As indicated at 38, the image depicts the aircraft standing on one wing.

The purposeof the rounabout light path is to that of the lower conjugated optical system.

The lower objective LO includes a prism 40 and an objective lens ll. with a reticule 42 in the focal plane of the lens ll. ."I'he image of the aircraft I3 is received by-the prism 40 along the line 43 and isreflected vertically upward along the line H through the lens 4| and reticule 42 In the field F a target airplane 13' is shown.

In normal flight. the wings ll of the airplane extend in a horizontal plane and therefore perpendicular to the vertical line V-V and to the objective plane. As indicated by dotted lines I! and I6, stereoscopic images of the field F, including the airplane ii, are carried by light rays to the objectives R0 and By optical means, which will be hereinafter described, thetwo stereoscopic images are rotated90 and are carried to and through the eye pieces LE and RE, and in the vision of the observer form a fused image I wherein the image I! of the airplane II will appear standing on one wing, or perpendicular 'tothehorimntalocularplanew. Also,byuse ofreticules within the range flnder. as will be hereinafter described, distance markers II arecaused appear in perspective in the image I,

and erector lens I", after which it impinges upon a diagonal reflector shown as a mirror 45. To the right of the mirror 45 there is a diagonal mirror 46, and adjacent the mirror 46 there is a diagonal mirror 41; Above the mirror .41 is another diagonal mirror 48 aligned with the eye piece LE. The mirrors, 41, and 48 are arranged so that the image will be carried rightward along the line b. toward the observer along the line il, upward along the line 52 and again toward the observer along the line 53 which passes through the eye piece, producing in the left eye of the observer an image I4 which likewise stands on a wing in conjugated relation to the image indicated at 39. It will be understood that these two stereoscopic images are fused in the vision of the observer in the manner described with relation to Fig. 1.

As indicated in Fig. 2, each of the conjugated optical systems may have lamps ID for illumination of the reticules, these lamps being controlled as to light intensity by use of a rheostat ll in the supply circuit 82 through which the lamps are energizable. Also, sunshields and filters may be employed in accordance with prior art practices. In all or the forms of my invention, means may be employed to vary the spacing or the eye pieces so as to correspond to the interpupillary distance of the observer. To illustrate this, Fig. 1 shows the eye piece LE supported by a slide 85 arranged to be moved toward and away from the eye piece RE by a screw 81 with threads to engage a bracket 88 and opposite hand threads to engage an internally threaded member 89 connected to the'slide 85 by an arm d. Both the eye piece [End the mirrors d? and 48 shown in Fig. 2 swivel about the axis 5! where the eye piece is adjusted for interpupillary distance. For

example, when the eye piece LE is swung around th axis represented by the line 59 to the position indicated by dotted lines LE, the mirror d8 will move along the arc some the position Q8 and the mirror 4? will rotate on the axis El through a like angle as indicated by dotted lines .el'.

In the range finder shown in Figs. 1 and 2, the

observer faces toward the target, or as otherwise expressed, the axes of the eyepieces extend near ly parallel to the lines along which light rays travel from the target to the objective openings.

In Figs. 3 and; I show a simple form oi my invention, using a minimum number of optical ele. ments, and so constructed that the observer does not lock outward toward the target, but looss laterally and at substantially right angles to the plane defined by the vertical base of the range finder and the target, such plane being vertical during normal horizontal flight of the aircraft.

As shown in Fig. 3, this simple form of the invention includes a relatively short upper tube 536 and a longer lower tube 92. The tubes Si and 92 are respectively supported by hollow bodies and st containing overlapping portions to and which support a left hand eye piece LE and a right hand eye piece EL? in side hy side relation.

The bodies as and St are connected by parallel I spacing of the portions and and likewise the spacing of the eye pieces LE and RE, may be varied and the upper and lower tubes ti and s2 yet maintained with their axes in accurate par allel relation. The parallel link means comprises plates of metal such as spring steel having their nels to extending from the front to the rear edges thereof adjacent thepoints of connection of the members es and as, so as to form relatively this web portions to at which the flexing action will tel-re place when relative lateral movement be tween the members so and as occurs. This lat: eral movement or adjustment is accomplished by means of a screw see extending from a lug lot which projects downwardly from the body es to 9, lug; its which projects upwardly from the body at. The upper and lower ends respectively of the tubes 89 and fill have housings its and Edd in which reflectors of the optical system 02 the range finder are mounted, and other members of the optical system are mounted'in the tubes ti and 92, the housings es and as and the eye pieces LE andRE, such lens system being shown diagrammatically in Fig. 4. I

j In the housing Ice at the upper end or the tube ti, there is areflector, comprising a pentaprism I05 which receives the image of the target lflt. along the line lol and reflects the same down? ward one-the line me within the tube to an lint means @l in such a manner that the lateral .its image in proper relation to that receives the image of the target along a line H8 and reflects the same upwardly along a line Ht within the tube 92. Adjacent the upper end of the tube 92, within the housing 9d, there is a reflector in the form of a simple triangular prism H6. Along the line 5 are placed an objective lens ill, a reticule lit and an erector lens lit.

The reflector 866 carries the light rays toward the observer to an eye piece lens E26 mounted within the left eye piece LE. As in the rest oi the range finder shown herein, the reticules of Fig. i are disposed in focal planes of their respective lens systems and arrangement oi the reflectors is such that the images of the target represented diagraatically at lot will appear rotated through angles of so. It will be noted that the upper optical system is short and dispcnses with an erector system, yet it presents presentedby the longer lower optical sysmm which contains such an erector system. I

In the form of range finder shown in 5, referred to as type D for the reason that it ploys dove prisms therein, the optical systems leading respectively to the left and rigl'rt eye are composed of the some elements, in reversed or antisytometrlcal position. The lower leg of the range finder shown in Fig. 5 has an objective mirror to receive the image along a line 55 and to reflect this image upward along the vertical line 53% to the mirror M which reflects the image for= waroly along line e27 through the eye piece E. Adjacent the mirror M there is an objective lens F, followed by a retlcule R. Erecting lenses L andL' are employed, and between them a clove prism D is placed and is disposed at an angle of 45 with respect to the plane defined by the lines 555 and thereby rotating .the image through an angle of so. In a similar manner but in reversed or antisymmetrical position, the upper optical system oi the range finder receives the image along a line 5%, and by the mirror M objective lens W, erecting leiises L and L dove prism D mirror M i-and eye piece E, the image is carried along the lines so and til to the right eye oi the obsewer. The reticule R is preferably placed lnthe focal plane of the objective lens The dove prism 13 is rotated in the opposits direction from the dove prism D to give the same rotation of the target's image through an optical system disposed in reversed position to the optical system which has therein the dove prism D. g

The dove prism acts as a third mirror lntho light path of each leg of the'range finder. The

' images are therefore mirror iges in which the designations right and left have the opposite coordinations with up and down to that in the real field. This, however, is not considered objection= able because the images appear to be standing on a wing anyhow. To facilitate identification of right and left in communication withobserver and pilot, 'a small r and 1! may be engraved in the top and bottom parts of the reticule. The same expedient .may be resorted to in the following. two types which also present mirror images.

The range finder shown in Fig. 6 is very similarto the range iindershown in Fig. 5 but avoids use of the dove prisms D and D, replacing these dove prisms by two additional mirrors arranged in cooperation with other mirrors to produce the required image rotation. This range finder has downwardly and upwardly extending legs represented by the vertical lines 62 and 63. At the outer ends of the legs, or, in other words, the lower and upper ends thereof, the mirrors M and M are placed. Along the lower leg 62 are arranged the optical members F, R, L,'and M, and along the upper leg are arranged the optical members I", R, L, and M". The mirrors M and M" are diagonally placed with relation to the legs l2 and 63 so that the images will be reflected at right angles to the legs, and, in addition, these mirrors M and M" are rotated bodily around theaxes represented by the legs 62 and '3 so as e to reflect the images laterailyalong the horizontal lines 64 and. N, the images then being reflected along forwardly extending lines 68 and I1 assas-re the same upwardly along the line ll. The mirror M at the upper end of the line H is diag-. onally disposed so as to reflect the image along the line III which lies in a horizontal plane, and is also rotated on the axis defined by the line 14, the rotation of the mirror M causing rota- .by mirrors M and M The images brought to the eyes of the observer through the eye pieces E and E are identical except for the stereoscopic parallax; It should be understood that the term forwardly herein refers to. the direction of travel of light rays from the target to the eye .the upper and lower legs of the range finder are sloped forward. Accordingly, in Fig. '1, the legs 82 and I of the arrangement shown in Fig. 6 are sloped forward as indicated at 62' and C3 .in Fig. '7. In order to obtain a 90' image rotation, it is necessary to swing the lines 84 and 65 from the positions in which they are shown in Fig. 6. As shownat 84' and 65', in Fig. '7, these lines of reflection between the mirror M and M" and M" and M'" instead of being aligned, slope forwardly in a horizontal plane toward the position of the observer. In the previously described form of my invention, the optical axes of the eye pieces are parallel to the line of sight to the target, so that the observer looks in the same direction as the tion of the image as indicated at IS. (The other leg of the range finder, namely, the upper leg, has mirrors W and M corresponding to the mirrors M and M, but in order to give proper rotation of the image transmitted by the upper leg of the range finder, it is necessary to employ the two additional reflective members 1n and m. The mirror M" is positioned so as to reflect the image along the line I! which is nearly parallel to the line of inception II. The mirror m reflects the image upwardly along theline ll, and. the mirror m reflects the image along the line ll through the eye piece E. p

In Fig. 9 I show reticules 21' and 42 comprised of discs of transparent material having the markers ll thereon. These reticules are substantially identical, differing only in the horizontal displacementsof the numbered markers II from the vertical center lines. H thereofi To illustrate this, I have in Fig. 9 diagrammatically shown a distance t separating the upper ends of the axes tit-a and the distance D, slight- 1y greater than the distance t, separating the lower ends of the axes H. In the preparation of these reticules, the markings ll are graphically or mathematically laid out to very large scale and then are photographically reduced to proper finally usable size. As indicated at I20, a centrally disposed X is employed to indicate a distance of 10 units from the observer, and a number of the markings X are distributed in a pat-' tern around the center of the reticule, as indicated at l2l, at their properly computed lateral parallax displacements.

In each reticule 21 and 42, in addition to the marks X, there are three systems of marks, each of which includes characters referring to distances nearer and farther than the a p rent distance of 10 units. One of these systems, in-

- dicated at I22, is disposed nearly along the vertiobjectives of the range finder. In the form of the invention'shown in Fig. 8, it.is arranged that the observer looks into the eye pieces in a lateral direction, these eye pieces being disposed sideways with respect to the plane defined by the objectives, thus accomplishing a 90 rotation ofv the field without an odd mirror in either leg of the range finder and without use of dove prisms. The image, therefore, will appear right-side-to as though merely rotated and not mirror-reflected.

This, however, does not accomplish a saving in mirrors, for the reason that two additional mirrors are required in one of the legs to bring the images to the observer at the same rotation instead of oppositely rotated. Re ring to Fig. '8, the observer looks into the eye eces E and E so that the images are brought to his eyes along the horizontal lines Ill and l l. However, the lines 12 and 13 along which the light travels from the target aircraft II to the objective mirrors M and M, extend nearly horizontally in a vertical plane which is perpendicular to the eye piece axes III and 1!. The mirror- M- at the lower le receives'the image along the 'line 12 and reflects cal center line H. Another system, I28, comprises indicating characters disposed alonga line which passes through the center of the reticule and slopes upwardly from left to right. -'llhe third system of marks, I, is disposed along a line sloping upwardly from right to left and passing through the center indicated by the character X of the system-ill. In the system, the large numerals 8 to I represent distances of six bun dred to nine hundred units, and the smaller numerals, ll,.l2, i8, i4, and II, represent the distances eleven hundred, twelve hundred. thirteen hundred, fourteen hundred, and fifteen hundred units. In the use of the range finder, thepattern of the reticules in the fused image brought to the observer, as indicated in Fig. l

the image brought to the vision of the observer,

. comparison of its distance with the apparent distances of the markings of the recticules will enable the observer to judge the distance of the target from the range finder with practical ac- 1 curacy. Each of the reticules set forth in the disclosure has characteristic features such as described in the foregoing several paragraphs.

an angle of approximately 90 to said objective I claim my invention:

1. In a range finder for binocular viewing of a field, the combination of: means establishing a base for the range finder; objectives near the ends of said base to receive light from said field; a pair of eye pieces in an ocular plane disposed at an angle to said base; and optical means to carry images of said field from said objectives to said eye pieces and to rotate said images through an angle corresponding substantially to the angle of said ocular plane to said base.

2. In a range finder for binocular viewing of a field, the combination of: means establishing a vertical base for the range finder; objectives near the ends of said base to receive light from said field; a pair of eye pieces in a horizontal ocular plane disposed at an angle to said base; and optical means to carry images of said field from said objectives to said eye pieces and to rotate said images through an angle of substantially 90.

3. In a range finder for binocular viewing or a field, the combination of: means establishing a base for the range finder; objectives near the.

ends of said base to receive light from said field; a pair of eye pieces inan ocular plane disposed at an angle oi substantially 90 to said base; op tical means to carry images of said field irom said-objectives to said eye pieces and to-rotate said images through an angle oi substantially so; and means enabling the observer to gauge the apparent parallax of a target appearing in the field of view of the range finder.

d. In a range finder for binocular viewing oil a field, the'combination of: means establishing a base-for the range finder; objectives near the ends oi said base to receive light irom said field;

a pair of eye pieces in an ocular plane disposed at an angle oi substantially 96 to said base; optical means to carry images of said field from said objectives to said eye pieces and to rotate said images through angles oi substantially 90;

and reticule means in the focal plane of at least one pair of said optical means to bring into said images a system of range marks by which the apparentparallax ot a target appearing in said field. may be gauged.

5. in a range finder for binocular viewing of a field, the combination of: means establishing a base for the range finder; objectives near the ends of said base to receive light from said held: a pair of eye pieces in an ocular plane disposed at an angle to said base; optical means to carry images of said field from said objectives to said eye pieces and to rotate said images; means to adjust the interpupillary distance between said eye pieces; and a pair of parallactically conju gated. reticules. 6. In a range finder for binocular viewing oi a field, the combination oi: means establishinga base fox-the range finder; objectives near the ends of said base to receive light from said field,

said objectives defining an objective plane; a pair of eye pieces-in an ocular plane disposed at an angle to said base and at an angle to said objective plane: optical means to carry images of said field from said objectives to said eye pieces and to rotate said images; and a pair of parallactically conjugated reticules. I

(.In a range finder for binocular viewing oi a field, the combination of: means establishing a base for the range finder; objectives near the ends of said base to receive light from said field, said objectives defining an objective plane; a pair of eye pieces in an ocularplane disposed at an angle of approximately 90 to said base and at plane; optical means to carry images of said field from said objectives to said eye pieces, said optical means having parts to rotate said images through angles of approximately and a pair of parallactically conjugated reticules.

8. In a range finder for binocular viewing of a field, the combination of means establishing a vertical base for the range finder; objectives near the ends of said base to receive light from v said field; a pair of eye pieces in a horizontal a vertical base for the range finder; objectives near the endsof said base to receive light from said field; a pair of eye pieces in a horizontal ocular plane disposed at an angle to said base;

and optical means to carry images of said field ,irom said objectives 7 along said base to said ocular plane, then laterally and rearwardly to said eye pieces, said optical means including parts to rotate said images through angles of substantially 90.

10. In a range finder, t e combination of: a

air of eye pieces dispose in side by side relation in aneye piece plane; a pairv of optical systems, each being arranged to bring a target image to one of said eye pieces; separate supporting means for each of said optical systems and its associated eyepiece; parallel link means connesting said supporting means for parallel relative bodily movement in a direction to change the distance between said eye pieces; and adjnstment means for causing said relative movemerit of said supporting means.

ii. In a range finder, the combination of; a pair, of eye pieces disposed in side by side relatic-n in an eye piece plane; a pair of optical systems, each being arranged to bring a target image to one of said eye pieces; separate supporting means for each of said optical systems and its associated eye piece; parallel link means connecting said supporting means for parallel relative movement in a direction to change the distance between said eye pieces, said link means comprising a pair of plate members with the end portions thereof connected to said supporting means, said plate members being thinned near the ends thereof so that they will be more fiexible at such points than intermediate the ends thereof and so that when said supporting means are moved together or apart, principal fiexure of said plate members will occur at said thinned portion thereof; and adjustment means for causing said relative movement of said supporting means.

12. In a range finder for binocular viewing of a field, the combination oi: means establishing a vertical basefor the range finder; objectives near the ends of said base to receive light from said field; a pair of eye pieces in a horizontal ocular planedisposed between said objectives upper than in the lower of two conjugated optical systems; and a pair' of parallactically conjugated reticules.

13. In a range finder for binocular viewing of a field, the combination of: means establishing a vertical base for the range finder; objectives near the ends of said base to receive light from said field; a pair of eye pieces in a horizontal ocular plane disposed between said objectives and closer to the upper of said objectives than to the lower; optical means to carry images of said field from said objectives to said eye pieces, said optical means having parts to rotate said images through an angle of substantially 90, and having more reflectors in the shorter upper than in the longer lower of two conjugated optical systems; and a pair of parallactically conjugated reticules.

14. In a. range I finder the combination of: a pair of eye pieces disposed in side by side relation in an eye piece plane; a pair of reflectors disposed one a shorter distance above one or said eye pieces, the other a longer distance below the other of said eye piece, each adapted toreceive an image of the distant field lying to one side of the observer; optical means to carry each of said field images in a rotated orientation to one of said eye pieces respectively; and means to gauge the parallax of distant field obiecta.

15. In a rangefinder. the combination of: a pair of elongated supportaeach having an eye piece end and an objective end, said supports being disposed so as to lie in spaced parallel planes and said eye piece ends being in side by side relation; an optical system carried by each.

of said supports comprising an objective, an

eye piece and optical means for transmitting an image from said objective to said eye piece; and parallel motion mechanism holding said supports in parallel relation and permitting bodily movement thereof together and apart whereby the distances between said eye pieces may be varied.

16. In a range finder, the combination of: a pair of eye pieces disposed in side by side relation in'an eye piece plane; a pair of optical systems, each being arranged to bring a target image to one of said eye pieces; separate supporting means for each of said optical systems and its associated eye piece; and means connecting said supporting means for relative bodily movement together and apart so as to change the distance between said eye pieces while at the same time holding said supporting means and the optical systems thereot in cooperative relation.

v WOLFGANG B. KLEMPERER. 

